1. Field of the Invention
The invention relates to a motor's stator for a household fan, and more particularly, to an improved motor's stator design with less coils, more torsion output and increased output efficiency.
2. Description of the Related Art
Conventional household fans employ a squirrel-cage rotor's motor as power source. As shown in FIG. 1, the stator 30 of this squirrel-cage rotor's motor is formed by stacking up a plurality of silicon steel sheets 3 with the dimension of 75 mm×75 mm. Meanwhile, the stator 30 includes a large hole 31 in the center thereof for receiving a rotor 5 with diameter of 44 mm. A plurality of slots 32, around which a coil 4 is wound, is provided along the circumference of the middle hole 31. After the stator 30 and the rotor 5 are assembled (see FIG. 2), the rotor is received within the middle hole 31 of the silicon steel sheets 3 and located at a clearance of 0.7±0.05 mm to the internal circumference of middle hole 31. After the current flows through the coil 4, a magnetic field is created to bring the rotor 5 into rotation. At the same time, the fan's blades are revolved. And the above-mentioned is a commonly used four-pole motor with sixteen slots 32. However, reasons for high temperature created during the rotational operation of the household fans lie in the large resistance of the copper wire, the magnetic resistance loss due to the clearance between the rotor and the stator and the iron loss due to the division of the partition magnetic field. Besides, these factors would lead to an adverse effect on the output efficiency of the motor.
In order to avoid the above drawbacks, a Taiwanese Utility Model Application (TW 89201451) discloses a structure of a motor's stator for a household fan in which the stator in form and configuration is improved. The middle hole of the stator is enlarged to 48 mm for accommodating a rotor with larger diameter. Accordingly, the actuation current, the operational temperature, the weight and the production cost are all reducible. In practice, the optimal revolutions are 950 rpm which is much lower than the above-mentioned four-pole motor with 1600 rpm, and the greater revolutions always cause trouble in application and design. Under the restriction of the number of the slots 32 of the four-pole motor's stator and their clearance, a desired torsion can't be reached. The rotation speed is always reduced or a problematic rotation easily occurs under influence of external forces (e.g. an adverse wind). All of these are also disadvantages of the TW 89201451.